ON BOARD WATER ANALYSIS

Water samples were taken from the bottles immediately after the recovery on deck, and filtrated trough 0.45 $\mu$m cellulose acetate.

The INGV group analayzed Fe$^{++}$ by a Lambda-25 Perkin-Elmer U-V spectrophotometer, while CO$_3^{--}$, HCO$_3^-$ and pH were detected by a Titralab 845 titroner. Eh and temperature were also measured by a meter. TQ samples were acidified with Suprapure HNO$_3$ 0.18 mol. and stored in the refrigerator at 5°.

The UNICH team measured Si and sulphydes on the whole sample by a Smart 2 LaMotte Colorimeter. Metals (among them Al and Mn) chloride, bromide and iodine were detected on some selected samples.